To tackle the energy crisis, researchers have developed many ways to extract renewable energy from Nature, such as solar energy, geothermal energy, and tidal energy. Nevertheless, many sources of renewable energy share the same problem that energy generated cannot be stored easily, and people have no control over when they wish to use it. For example, the use of solar energy is limited to daytime only. In fact, energy storage is also essential to non-renewable energy, as it ensures that no energy is wasted when the energy demand is less than the supply. Chemists, therefore, are devising new methods for energy storage in form of chemical energy.
Recent research directions
Solid-state lithium battery link
Looking for safer lithium-ion batteries with higher energy density, intensive research is ongoing to develop solid-state batteries. A solid electrolyte can act as a separator between the cathode and the anode, and hence allow the use of energy-dense anode materials as it is much less likely for the electrodes to have direct contact accidentally.
Rechargeable zinc-manganese battery link
Researchers improved the zinc-manganese battery by separating the electrodes and electrolytes into three chambers with ion-exchange membranes. In this version of zinc-manganese cell, potassium sulfate as the electrolyte is placed in the middle chamber to separate zinc electrode immersing in potassium hydroxide solution from manganese dioxide immersing in a solution of sulphuric acid and manganese sulfate. With this advancement, a two-fold increase and a three-fold increase were recorded for voltage and energy density respectively. Furthermore, this cell is rechargeable.
New electrochemical batteries link1 link2
With the advancements in material science, more and more novel materials are put to test for the ability to make better batteries, including graphene and its derivatives and boron-nitride. Graphene, being an excellent electrical conductor, is also light-weighted and durable. On the other hand, boron-nitride has a tuneable bandgap by doping and introducing defects and is resistant to heat and force.
Thermochemical energy storage link
Thermochemical energy storage systems make use of chemical reactions which release heat or absorb heat. The reported heat battery is composed of a salt and water. When heat is applied, the hydrated salt will be dehydrated, giving you back the salt and water. The heat is then stored and will be released when the salt is hydrated again.
Hydrogen storage link
Hydrogen by itself is a clean fuel as only water is produced. It releases a great amount of energy when combusted or used as fuel in fuel cells. However, the storage of hydrogen in a safe and inexpensive way remains a challenge. Some promising candidates of liquid organic hydrogen carriers are reported in this article.